Electroactive nanostructured polymers and organic-inorganic hybrid materials

Novel electroactive nanostructured polymers and organic-inorganic hybrid materials have been successfully developed for electrochemical, sensory, and tissue engineering applications. For this new class of materials, electroactivity was introduced into silica matrix through the incorporation of a silsesquioxane precursor, N,N'-bis(4'-(3- triethoxysilylpropyl-ureido)phenyl)-1,4-quinonenediimine (TSUPQD). As a derivative of emeraldine form of aniline trimer, TSUPQD was synthesized from the reaction between one equivalent of aniline trimer and two equivalents of triethoxysilylpropyl isocyanate (TESPIC) and characterized by spectroscopic methods, such as FTIR, UV-Vis, MS, NMR, and XRD. The electrochemical behavior of TSUPQD was studied by cyclic voltammetry showing two distinct oxidative states in a reversible cyclic voltammogram after doping with a protonic acid. The intrinsic electroactivity of TSUPQD is similar to polyaniline was maintained. With the presence of two triethoxylsilane groups on each TSUPQD molecule, related mesoporous electroactive hybrid materials were prepared through surfactant templated sol-gel process. The resultant hexagonally patterned porous structures were studied by BET and TEM. The materials have large surface areas and pore volumes with pore diameters ranging from 2.1 to 2.8 nm. Porous structures give rise to improved electroactivity compared to their nonporous counterparts. Multicolor silica nanospheres were prepared by coating TSUPQD onto silica surface via intermolecular condensation reaction. By varying the particle size, surface area, and organic dopant, the nanospheres exhibit multiple colors. Furthermore, luminescent nanospheres were prepared when fluorescent organic acid was employed as dopant. These nanospheres demonstrated the promising potential as sensory materials for hydrazine detection. Electroactive self-assembled monolayers were evenly attached on glass substrates, followed by covalent bonding of an adhesive oligopeptide, i.e., cyclic RGD, on the aromatic amine terminals. The biocompatibility evaluation on resultant structures from PC12 neuronal cell cultures demonstrated that this bio-derivatized substrate well supported the cell adhesion and proliferation. It is more significant that this electroactive surface stimulated spontaneous neuritogenesis of PC12 cells. Electrospun PANI-contained gelatin fibers were also investigated as conductive scaffold for tissue engineering purposes. SEM analysis of the blend fibers containing less than 3 wt% PANI revealed uniform fibers with no evidence for phase segregation. DSC studies confirmed this result. To test the utilization of PANI-gelatin blends as a fibrous matrix for supporting cell growth, H9c2 rat cardiac myoblast cell cultures were evaluated in terms of cell proliferation and morphology.